Gen 4 Team suggestions please

So I have a team so far that consists of Slaking, Hera, and Metgross. I know Infernape and Blaziken are the downfall of my team so far already, but I was wondering if there were any other Pokemon that would easily take me out? and what are the best additions for my team? Baring in mind Id prefer to stick with the OU Metagame :)